As our environment becomes more and more polluted, and ever-increasingly more powerful toxic elements are isolated and released in our environment, there has been a great demand for methods or tools which can measure very very small amounts of chemical elements dissolved or suspended in air, water, and other industrial fluid mediums. One of the major difficulties involved in the conventional spectrophotometric apparatus used to measure an extremely minute amount of chemical elements dissolved or suspended in a carrier fluid medium is to isolate the change in the light intensity that is caused by the chemical element from other changes resulting from the physical and optical boundary conditions associated with the spectrophotometric apparatus. In other words, one has to know the precise reading indicated by the apparatus when the sample is perfectly pure. Then, one can compare the reading on an impure sample with the reading on the pure sample and determine the degree of impurity. The dilemma is that the actual reading on a contaminated sample has to be always compared with an old reading on a perfectly pure sample because there is no way to measure a perfectly pure sample and a contaminated sample with the same apparatus at the same time and, consequently, there is always a doubt about the old reading on a perfectly pure sample which changes in time as the condition of the apparatus changes in time. This problem of uncertainity or of creeping error has no easy solution and is being tackled by an extremely painstaking and time-consuming process at the present time.
The primary object of the present invention is to provide a spectrophotometer or turbidity meter that measures the concentration of chemical elements or impurities accumurated in the mass boundary layer adjacent to a filter that blocks the movement of the chemical elements or impurities thereacross while allowing the flow of the carrier medium thereacross.
Another object of the present invention is to provide a spectrophotometer or turbidity meter that has a built-in reference reading that plays a role equivalent to the reading on the pure sample in the conventional spectrometer or turbidity meter.
A further object of the present invention is to provide a spectrophotometer or turbidity meter employing a single light path-single sample cell combination that replaces the dual light path or dual sample cell method employed in conventional spectrophotometric apparatus.
Yet another object of the present invention is to provide a spectrophotometric technique that measures transient mass concentration within the mass boundary layer adjacent to a filter for a finite period immediately following a washing period wherein this combination of washing-measuring cycle is repeated over and over in order to provide a continuous reading on the sample continuously passed by or through the filter.
Yet a further object of the present invention is to provide a spectrophotometer that has enough versatility to measure an extremely low level of impurity as well as a high degree of impurity, which versatility is provided by means for varying the period of each washing-measuring cycle.
Still another object of the present invention is to provide a spectrophotometer that is installed in-line and continuously monitors the medium flowing through the line without requiring frequent cleaning and calibration.
Still a further object of the present invention is to provide a spectrophotometer measuring the transient mass concentration in a mass boundary layer adjacent to an opaque filter.
Additionally another object of the present invention is to provide a spectrophotometer measuring the transient mass concentration in a mass concentration boundary layer adjacent to a light-transparent filter.
Additionally a further object of the present invention is to provide a spectrophotometer measuring the transient mass concentration in a mass concentration boundary layer adjacent to a light-reflecting filter.
These and other objects of the present invention will become clear as the description thereof proceeds.